Channel Change Delay

Archived from groups: alt.tv.tech.hdtv (More info?)

I've been looking at LC HD sets, and have noticed a lag when changing
channels. On my present CRT TV the channels change instantly. Is this lag
normal for all LC TV sets?

Archived from groups: alt.tv.tech.hdtv (More info?)

On Mon, 26 Sep 2005 11:33:09 -0700 Ernest Cassirer <erncass@foxinternet.net> wrote:

| I've been looking at LC HD sets, and have noticed a lag when changing
| channels. On my present CRT TV the channels change instantly. Is this lag
| normal for all LC TV sets?

Could elaborate on how you see this lag? During the time from when you
actually do the channel change, to when you see it in effect on the
screen, what happens:

1. The screen goes black (or some other color or fixed pattern).
2. The last frame of the channel you are leaving is frozen on the screen.
3. The channel your are leaving remains active and moving for the duration.

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Archived from groups: alt.tv.tech.hdtv (More info?)

Brian Kraft wrote:
>
> Dennis Mayer wrote:
>
> >If your digital Set Top Box is set to : DVI Auto there may be a
> >delay in switching channels if you have 1080i, 720p, 480p, &
> >480i a set as possible Format selections.... IF you force every
> >type of incoming program to 1080i... there should be no big delay
> >but SD 480i programs could suffer lesser picture quality...
> >
> >My TWC SA-3250-HD STB using Auto DVI to a Sony 34HS510 CRT set shows
> >a picture delay as the Sony figures out the Proper HD signal format
> >in use and displays that Format ID in the lower right hand screen corner..
>
> Initially, I set the output from the STB for all channels to 480p and
> this worked fine. Now we have our first HD channel in town; in 480p
> mode the STB squeezes it to 4:3, and then through DVI-D, the plasma
> EDTV expands the squeezed picture horizontally to full 16:9 aspect
> ratio. Unfortunately, that horizontal squeezing and expanding results
> in a picture with a vertical ribbed effect. So the 1080i signal looks
> best when the STB instead outputs 1080i and the EDTV scales that down
> to 480 lines; no vertical ribbed effect. However, this presents a
> problem if channel surfing in native mode; there's always signal shock
> as the EDTV takes a few seconds to adjust and sync to the different
> resolution. There are light flashes, green squares and other odd
> colorful shapes, and general chaos on the screen for a second or two
> for each resync. I don't want to damage the circuits of the DVI blade
> or EDTV, so the new 1080i HD channel isn't in the surf list or channel
> list at all; to select and view it I have to punch in the channel
> number. I explained above why I don't want to output from the STB all
> of the channels including the HD one, to 480p. How do you channel
> surf, if you have an EDTV, a STB, and a mixture of SD and HD channels?
> Do you surf through them in native mode, or not?


EDTV is 480p wide.....

A STB like a SA-3250-HD has these Auto DVI choices:

1080i, 720p, 480p wide, 480p, 480i wide, & 480i
and they could/should be selected for a HDTV monitor TV.

For Auto DVI using an EDTV select:
480p wide, 480p, 480i wide, & 480i

Here all HD channels would be shown in 480p wide (16:9)

Archived from groups: alt.tv.tech.hdtv (More info?)

Brian Kraft wrote:
>
> Dennis Mayer wrote:
>
> > EDTV is 480p wide.....
> >
> > A STB like a SA-3250-HD has these Auto DVI choices:
> >
> > 1080i, 720p, 480p wide, 480p, 480i wide, & 480i
> > and they could/should be selected for a HDTV monitor TV.
> >
> > For Auto DVI using an EDTV select:
> > 480p wide, 480p, 480i wide, & 480i
> >
> > Here all HD channels would be shown in 480p wide (16:9)
>
> My STB doesn't have 480p wide output; the aspect ratio choices for
> 480p are letterboxed in 4:3, cropped into 4:3, and squeezed into 4:3.
>
> It appears that a STB like the SA-3250-HD has this major advantage
> over mine, which is the LG LST-4200A.


There has to be a STB or EDTV SETUP menu item to

say that I have a 16:9 aspect ratio screen...

And yes, the STB should be set to 480p...... or 480p wide..

all you need is the 16:9 aspect ratio menu...

I have a Samsung T-451 for OTA STB...
I have a SA-3250-HD for a TWC (cable) set top box.

Archived from groups: alt.tv.tech.hdtv (More info?)

Brian Kraft wrote:
>
> Dennis Mayer wrote:
>
> > There has to be a STB or EDTV SETUP menu item to
> > say that I have a 16:9 aspect ratio screen...
> > And yes, the STB should be set to 480p...... or 480p wide..
> > all you need is the 16:9 aspect ratio menu...
> >
> > I have a Samsung T-451 for OTA STB...
> > I have a SA-3250-HD for a TWC (cable) set top box.
>
> The LG LST-4200A doesn't have any setup item to tell it I have a 16:9
> screen; I can select output formats, but all the output formats for
> 480p are various 4:3 ratios (Letter box, Cropped, or Squeezed).
>
> The manual does say that the Squeezed ratio "can be useful when used
> with 16:9 aspect ratio monitors..." The problem with that is
> expanding the squeezed output to full 16:9 doesn't look so good.
>
> What exactly is a "480p wide" signal anyway?

A 480p wide TV signal is called:
EDTV or FOX Networks original 'low buck HD plan'
or 480 progressive wide screen in 16:9
Wide implies the 16:9 picture detail aspect ratio.

In a pinch for more HD cameras, FOX used to throw in a few 480p
16:9 shots which is NOT HD resolution...
Last seasons (year ago) NASCAR races were shot in EDTV by FOX.




If your STB is set to
> "480p wide", is that actually 16:9 content "squeezed" into 4:3?

(1/6 yes... NO to squeezed into 4:3


My Samsung T-451 OTA STB is set to 1080i using component cables
since I have a Sony 34HS510 HDTV Monitor (34" 16:9 CRT)

My Cable SA-3250-HD STB is set to DVI AUTO with active modes
1080i, 720p, 480p wide, 480p, 480i wide, & 480i since
my Sony HDTV 'guts' can handle DVI signal & display all these
modes. If FOX sent me 480p wide on cable for a sports Pgm....
my TV shows EDTV (480p wide) quality picture in 16:9 etc...
I can usually tell that it is not 720p HD quality.....